WO2008019865A1

WO2008019865A1 - Aqueous foams, food products and a method of producing same

Info

Publication number: WO2008019865A1
Application number: PCT/EP2007/007272
Authority: WO
Inventors: Martin Leser; Jean-Baptiste Bezelgues; Eric Kolodziejczyk; Martin Michel
Original assignee: Nestec S.A.
Priority date: 2006-08-17
Filing date: 2007-08-17
Publication date: 2008-02-21
Also published as: MX2009002141A; EP1889544A1; AU2007286413A1; EP2059129A1; AR062430A1; BRPI0716064A2; US20100310746A1; US8778438B2; CL2007002403A1

Abstract

The present invention describes an aqueous foam comprising water, at least one polysaccharide and food-grade, interf acially active particles. The present invention also describes an indulgent shelf -stable foamed food product comprising this aqueous foam. The indulgent shelf -stable foamed food products of the invention have an improved foamed and modular product texture.

Description

Aqueous Foams , Food Products and a Method of Producing

Same

Field of the Invention

The invention relates to the incorporation of air or gas into food matrices which are viscous and difficult to foam. More particularly, it relates to aqueous foams and food products containing same having an improved and modular product texture. The invention further relates to a process of producing the foamed food products .

Background of the Invention

Viscous products are known on the market since they give to the consumer a gratifying and stable product quality. However, such products are often graded by the consumer as being heavy. One way to improve the acceptance of these products by the consumer is by incorporating air or gas into such products since this gives more lightness and delight to the consumer during consumption of these viscous products.

However, technically, it is not a trivial task to incorporate air or gas into viscous food matrices. It is well known that above a certain viscosity, it is very difficult to incorporate air in a significant amount. Most of the air added to the product during the whipping or foaming step is not incorporated into the viscous product and lost (Blow-by) . Moreover, the air is incorporated in form of large, polydisperse air bubbles into the viscous matrix. The bubble mean size, size distribution and bubble interface composition cannot be easily controlled, and the quality of the final produced product, i.e., stability over time and sensory attributes, cannot be assured.

Classically, in order to make and stabilize the foamed product, a stabilizer system consisting of an emulsifier system and a viscosifying agent has to be added to the aqueous bulk phase prior to the foaming step. The main drawback of this is, however, the limitation of making foams out of aqueous phases which are viscous due to the significant decrease of the diffusion rate of the emulsifier system from the viscous bulk phase to the bubble interface during the foaming process resulting in a unacceptable final product quality (broad gas bubble distribution and inhomogeneous distribution of the entrained gas) and low shelf stability. So far the control and design of the texture of foamed products is mainly achieved by adding a viscosifying agent to the food matrix prior to the foaming step, leading to a low product quality if the viscosity of the liquid bulk phase is too high.

In order to make stable foamed products, specific emulsifier/stabilizer systems have to be added prior to the foaming step. For instance, US 6,368,652 Bl describes food products including whippable products which are stabilized by a specific surfactant combination, i.e., mainly consisting of a non-ionic surfactant and a minor amount of an ionic co-surfactant . The non-ionic surfactant is selected from monoglycerides while the ionic co- surfactant may be alkali salts of lactylated fatty acids, citric acid esters, succinated esters and diacetyl tartaric acid ester of monoglycerides. The ionic co- surfactants are used to swell the monoglyceride based lamellar liquid mesophases, i.e., to solubilize a large quantity of water into the inter-planar water layers of the bilayers making this mixture suitable as a structuring agent of the aqueous phase, fat replacer or foam control agent .

EP 1 366 670 Al describes a gas containing desert and a method for preparation thereof in which the gas bubbles are stabilized by partially coalesced fat. Aerated food products, in which the gas bubbles are stabilized by partially coalesced fat, are based on fat-containing recipes, since partially coalesced fats are known to stabilize gas/air bubbles and foamed products, such as ice or whipped creams. However, such fat-based aerated products show limited stability during shelf -life. The reason of this is related to the insufficient stabilization of the air bubble structure against Ostwald ripening, coalescence or creaming leading to an increase in the bubble size, bubble size distribution and change in interface composition.

It is object of the invention to provide a technology to incorporate air or gas into viscous food matrices enabling a better control and stabilization of the air/liquid interface during the aeration process.

It is another object of the invention to provide shelf- stable viscous and indulgent food products having a controllable air bubble structure, i.e., a stable air/liquid (bubble) interface and an improved shelf-life.

Summary of the Invention

The invention encompasses in one aspect, an aqueous foam as defined in claim 1 in which air is incorporated in form of small, monodisperse air or gas bubbles giving an indulgent foam. The interface which stabilizes the air bubbles is unique, since it consists of surface active food particles, such as particles made out of seeds, spices, spores, grains, sugar etc, or a particular emulsifier mixture leading to the formation of supra- molecular interfacially active aggregates or particles, such as lamellar surfactant particles or crystals, biopolymer aggregates, biopolymer-polysaccharide aggregates, biopolymer-surfactant aggregates, melanoidins, complex coacervates, nutrient crystals etc. The specific interface composition and structure is responsible for the exceptional stability of the incorporated gas bubbles in the indulgent foam product. The exceptional stability of the bubbles is related to the fact that the bubbles are stabilized by supra-molecular aggregates or particles which show interfacial activity. The mixture does not contain partially coalesced fat, and therefore, provides a superior stability of the final food product than products stabilized by partially coalesced fat.

The invention encompasses a foamed food product as defined in claim 17.

The invention encompasses in a second aspect a process of producing the stable air/gas bubbles in a continuous way using 'adapted' high shearing devices. Not all classical shearing/whipping devices can be taken. For this invention suitable shearing devices are devices which allow to let adsorb or attach the supra-molecular interfacially active aggregates or particles to the newly created air/gas bubbles during the incorporation of the gas/air. This requires shearing/whipping devices which allow to deliver a local shear rate ranging between 1200 and 2200 s^"1 and providing a suitable residence time of the matrix within the shearing device ranging between 35 s to 80s, which allow the adsorption or attachment of the interfacially active particles or aggregates to the newly created air bubbles. The formation of the interfacially active particles or aggregates can occur already in the bulk phase, i.e., prior to the attachment to the gas bubbles, or only after adsorption of surface active material in its molecular form. In the latter case, the supra-molecular aggregates (particles) are directly formed at the gas bubble interface .

The invention encompasses in a third aspect a process of incorporating the air bubbles into a viscous matrix leading to the formation of the indulgent foam. The process is comprising (i) the continuous formation of air bubbles stabilized by the interfacially active supra- molecular aggregates in an aqueous and non fat low viscous food matrix and (ii) adding/mixing continuously a viscous, matrix to the pre- foamed aqueous air/gas bubbles dispersion (primary foam) giving the product the indulgence character.

The invention encompasses a process of producing a shelf- stable foamed food product as defined in claim 21. The air bubbles contained in the food product obtained are stabilized by the interfacially active particles. The bubble dispersion is mixed in-line with the viscous matrix without inducing the disruption of the bubbles present in the pre-foamed product (no bubble coalescence, i.e. no lost of the stable bubble interface properties created in the first step) . The exceptional stability of the bubbles created in the first step is achieved due to the involvement of interfacially active particles at the bubble interface. The interfacially active particles are either created before foaming or during the foaming step.

The viscosity of the aqueous solution in the first step which allows the creation of a fine and stable primary foam, stabilized by interfacially active particles is not exceeding 2 Pa. s.

The supra-molecular food-grade interfacially active particles of this invention are selected from the group of seeds, spices, seasonings, spores, cloves, pepper, fennel, cumin, coriander, nutmeg, poppy grains, paprika, cinnamon, talcum, pollen of flowers, wheat germs, wheat bran, saffron, coconut, cacao, melanoidins, sugar crystals, milk proteins, ginger, curry, nutrient crystals or aggregates selected from the group of lamellar surfactant crystals, particles made out of protein aggregates, polysaccharide aggregates, particles made out of protein-surfactant aggregates, particles made out of protein-polyssacharide mixtures, particles made out of polysaccharide- polysaccharide mixtures, particles made out of polysaccharide-protein phase separating mixtures, or mixtures thereof. The interfacially active particles may be already surface active on their own or get their surface active properties after grinding of the particle material and/or by addition of a low molecular weight emulsifier which adsorbs to the interface of the particles. The interfacial activity of the particles of this invention (adsorption to the bubble interface or desorption from the bubble interface) can be followed using classical surface tensiometry, such as the Wilhelmy plate of Drop shape or Drop volume or Bubble pressure tensiometry (R. Miller et al . , SOFW-Journal 130, 2-10

(2004)) . The adsorption/attachment of the interfacially active particles to the gas or air bubbles can be followed by light and/or electron microscopy. Especially polarized light or fluorescent microscopy is a suitable technique to visualize the attachment of interfacially active particles at the air-bubble surface (see Figure 5)

The term ^x Interfacially active particles' is used herein to describe colloidal particles, i.e., supra-molecular aggregates, having a diameter between 0.5 nm up to several tens of a micrometer, which act in many ways like emulsifiers in the sense that they are able to adsorb or attach to a fluid-air interface. The unique feature of the adsorbed particles is that their attachment at the air- water interface is irreversible. This is clearly not observed using commonly used foaming agents, such as low molecular surfactants, such as Tween 80, or polymers, such as whey proteins, which are adsorbed in a reversible way and desorb again after a certain time (an adsorption/desorption equilibrium between the bulk and the bubble interface is established) . The irreversible attachment of the particles to the fluid-air interface of the gas bubbles gives the bubbles the remarkable stability against coalescence or Ostwald ripening.

According to the present invention, the interfacially active particles can be created in different ways: One way to create interfacially active particles is by using low molecular weight ionic emulsifiers, heating the aqueous dispersion above their Krafft temperature and cooling the dispersion down again to room temperature while stirring. During the cooling step the particles are formed. The foaming of the aqueous phase can be during the cooling step or just after the system is cooled down to room temperature. The used emulsifier can be a mixture of different emulsifiers or can be used singly.

The shelf-stable indulgent foams are storable at temperatures above 0⁰C including room temperature without loosing the gas present in form of tiny gas bubbles in the product. The indulgent foam of this invention has a new light texture and structure and provides the possibility to make indulgent and stable low- or no fat products as gas bubble containing products, in which the oil droplets are replaced by gas bubbles to give the indulgent character to the product.

The invention can also be used to make new environmentally friendly foamed products in the area of cosmetics, nutrition, medicine, agro-chemicals, chemicals, drugs, pharmaceutics.

Brief Description of the Drawings

Further features and advantages of the invention can be ascertained from the following detailed description that is provided in connection with the drawing described below:

Fig. 1 shows lamellar surfactant crystal particles at the macroscopic air-water interface viewed by

Brewster Angle Microscopy.

Fig. 2 shows diminishing bubble experiments illustrating the stability at room temperature of a single air bubble stabilized by surface active particles against Ostwald ripening. Fig. 3 illustrates the foam stability of an indulgent foamed product according to the invention versus a conventionally foamed product.

Fig. 4 shows a comparison of the bubble size distribution in a dessert mousse produced using a conventional foaming process and the 2 step process using SSL lamellar crystals as bubble stabilizer.

Fig. 5 shows a microscopic picture obtained using polarized light of a foam stabilized by SSL lamellar crystals, which are attached to the gas bubble interface . The arrows indicate the SSL particles at the air bubble interface.

Detailed Description of the Preferred Embodiments

The aqueous foam of the present invention comprises air/gas bubbles stabilized by supra-molecular aggregates or particles which show interfacial activity. Fig. 1 shows lamellar surfactant crystal particles at the air-water interface viewed by Brewster Angle Microscopy. The crystal particles are formed of sodium steaoryl lactylate (SSL) . Stabilization of the air bubbles occurs by adsorption or attachment of the crystal particles to the created air bubbles during incorporation of air.

The extreme stabilization of the bubbles formed in the aqueous foam have been confirmed in diminishing bubble experiments shown in Fig. 2. The diagram of Fig. 2 shows the stability of a single air bubble against Ostwald ripening at room temperature. The stability of the bubble is characterized by the decrease of the measured bubble R³ normalized by the bubble radius R₀ ³ at the beginning of the measurement. The bubble is stabilized by (i) SSL lamellar crystal particles and compared to the stability of a single bubble stabilized by (ii) Tween 80 (a soluble surfactant present in its molecular form at the bubble surface) or (iii) whey protein molecules. Note that the stability of the bubble stabilized by SSL particles is significantly higher than the stability of the bubbles stabilized by the commonly used surfactants, such as the low molecular weight surfactants such as Tween 80, or proteins, such as the whey proteins. The enormous stability of the bubble when stabilized by particles is due to the fact that the particles are irreversibly attached to the air bubble interface. The particles sitting at the air bubble interface can be easily visualised by means of polarized light microscopy (see Fig. 5) or fluorescence light microscopy

A polysaccharide or hydrocolloid is advantageously present in the aqueous foam upto a certain concentration as it allows the foam to have a certain viscosity which helps to increase the stability of the primary foam.

In a preferred embodiment of the invention, the polysaccharide or hydrocolloid is present in an amount of 1 to 60 wt. -% based on the components of the aqueous foam. More preferably, the amount of the polysaccharide or hydrocolloid in the aqueous foam is in a range of 10 to 50 wt.-%, specifically in a range of 20 to 40 wt.-%.

Principally, every polysaccharide or hydrocolloid which is used to viscosify an aqueous solution, can be used in the aqueous phase, as long as it is water soluble and capable of imparting a certain, but not too high viscosity to the aqueous foam. The viscosity of the primary aqueous solution should not exceed 2 Pa. s, preferably ranging between 0.5 to 1 Pa . s . Preferably, the polysaccharide is selected from at least one of starch, cellulose gums and derivatives thereof. Specifically, the polysaccharide is a starch derivative or others hydrocolloids like carrageenan, guar, caroube, acacia gums, xanthan, alginates. In a particularly preferred embodiment of the invention, the starch derivative is maltodextrin. In a preferred embodiment of the present invention, the food-grade, interfacially active particles are present in the primary aqueous phase in an amount of 0.5 to 10.0 wt . - % based on the components of the aqueous foam. More preferably, the amount of the food-grade, interfacially active particles is in a range of 1.0 to 5 wt.-% based on the components of the aqueous foam. More preferably, the amount of the food-grade, interfacially active particles is in a range of 1.0 to 3.0 wt.-% based on the components of the aqueous foam.

In a further preferred embodiment of the invention, the food-grade, interfacially active particles comprise at least one lamellar crystal forming surfactant selected from sodium stearoyl lactylate (SSL) , calcium stearoyl lactylate (CSL) , salts of fatty acids, lactic acid ester of monoglycerides (LACTEM) , citric acid ester of monoglycerides (CITREM) , succinated ester of monoglycerides (SMG) , diacetyl tartaric acid ester of monoglycerides (DATEM) , phospholipids, sucrose esters, polyglycerol esters, propylene glycol stearate, sorbitan monostearate (SMS) , sorbitan tristearate (STS) . In a particularly preferred embodiment of the present invention, the lamellar crystals forming surfactant is sodium stearoyl lactylate (SSL) .

In a further preferred embodiment of the invention, the food-grade, interfacially active particles comprise at least one food-grade particulated material, i.e., a food- grade material which is present in form of particles which have a diameter not larger than several tens of a micrometer. If necessary, in order to get the desired particles diameter, the particulated material can be grinded or treated with any suitable technology to get the desired particle sizes. The particles may already be surface active on their own. If their surface activity is not yet high enough allowing the adsorption or attachment of the particles to the gas bubble surface or interface, an emulsifier can be added which adsorbs to the particle interface and makes the particle surface active. The food- grade, interfacially active particles are selected from the group of seeds, spices, seasonings, spores, cloves, pepper, fennel, cumin, coriander, nutmeg, poppy grains, paprika, cinnamon, talcum, pollen of flowers, wheat germs, wheat bran, saffron, coconut, cacao, melanoidins, sugar crystals, milk proteins, ginger, curry, cell wall extracts, nutrient crystals or mixtures thereof. The nutrient crystals are made of water- insoluble nutrients forming crystals in water. Examples are phytosterols, cholesterol, hesperidin, lycopene, carotenoids, flavonoids, antioxidants or other crystal forming nutrients .

According to the present invention, the interfacially active particles can be created by forming soluble surfactant-protein, protein-protein or protein- polysaccharide complexes.

The stabilized aqueous foams can be aerated in any device suitable to create high overruns. Examples of such devices are a colloidal mill or rotor-stator type devices which allow to deliver a local shear rate ranging between 1200 and 2200 s^"1 and providing a suitable residence time of the matrix within the whipping device ranging between 35 s to 80s. Moreover, membrane-based foaming devices can also be used. Such foaming devices allow formation of very fine and extremely stable aqueous foams stabilized by surface active particles.

The aqueous foam of the present invention is aerated to have an overrun of up to 500 %, preferably in a range of 200 to 450 %.

In principle, any food product may be foamed by the above- described aqueous foam. Examples of food products to be foamed are ice cream mixes, sorbet mixes, dessert mousse mixes, dairy products, fermented dairy products, soups, sauces, mayonnaise and beverages, dressings, liquid dairy products, creams, imitation creams, concentrated milks, condensed milk, non-dairy creams, toppings, chilled dairy, confectionery filling, candies, dough, batter.

The present invention also provides a shelf-stable indulgent, foamed food product having a light and pleasant foam texture. The air bubbles structure is stable at temperatures above O⁰C, even at room temperature, due to the very fine and extremely stable air bubble distribution in the food product. The interface which stabilizes the air bubbles is unique, since it consists of a particular particulated material or emulsifier mixture leading to the formation of supra-molecular interfacially active aggregates or particles, such as food particles made out of seeds, spices, spores, grains, sugar crystals etc, surfactant particles or crystals, biopolymer aggregates, biopolymer-polysaccharide aggregates, biopolymer- surfactant aggregates, melanoidins, complex coacervates. The surfactant particles or crystals can be selected from sodium stearoyl lactylate (SSL) , calcium stearoyl lactylate (CSL) , salts of fatty acids, lactic acid ester of monoglycerides (LACTEM) , citric acid ester of monoglycerides (CITREM) , succinated ester of monoglycerides (SMG) , diacetyl tartaric acid ester of monoglycerides (DATEM) , phospholipids, sucrose esters, polyglycerol esters, propylene glycol stearate, sorbitan monostearate (SMS) , sorbitan tristearate (STS) or mixture thereof .

The shelf- stable foamed food product according to the invention comprises 0.1 to 50 percent by weight of an aqueous foam (based on the finished food product) .

Fig. 3 illustrates the foam stability of an indulgent foamed product according to the invention versus a conventionally foamed product. The storage temperature is 40⁰C and the air bubbles are stabilized by surfactant particles made from a 1.5 % SSL (sodium steaoryl lactylate) dispersion. As can be seen from the percent foam volume of the foamed products, the foamed product according to the invention remains stable over a time period measured while the conventionally foamed product fails to retain in foam volume already shortly after preparation.

A food product of the present invention comprises the aqueous foam as described above to provide shelf-stable indulgent foam products. The overrun in the final indulgent product is in a range of 10 to 300 %. In a particularly preferred embodiment, the overrun of the final shelf stable product is ranging between 25 to 150%.

Further, the shelf-stable indulgent foam food products of the present invention are storable at temperatures above

0⁰C, even at room temperature without loosing their foamed structure. As the aqueous foam is stable by itself, it can be also used as an intermediate product which is then, as desired, used for further processing. Due to the absence of fat in the aqueous foam, it can be used in virtually all food products .

The shelf-stable foamed food products of the present invention have a light and pleasant texture. The texture perceived by the consumer is related to the amount of gas bubbles present in the indulgent foam. This can easily be modulated by varying the overrun in the primary aqueous foam and/or by varying the mixing ratio of the primary aqueous foam and viscous food matrix. It is possible to provide the shelf-stable foamed food products as stable low- fat products which are highly appreciated by the consumers as the aqueous foam contained in the shelf- stable foamed food products does not comprise fat components. In addition, due to the presence of a polysaccharide having a weak sweet taste, the aqueous foam can be easily used in food products in which an intense sweetness is not desired, such as in soups, mayonnaise and beverages . A process for producing a shelf-stable foamed food product as described above may comprise a two-step foaming process. In a first step a primary aqueous foam comprising water, at least one polysaccharide or hydrocolloid and interfacially active supra-molecular particles is formed, and, in a second step, said aqueous foam is added to a food product to be foamed.

In a preferred embodiment of the process of the present invention, the aqueous foam is formed by heating a mixture containing water, at least one polysaccharide or hydrocolloid and the ingredient being able to form interfacially active particles to a temperature in a range of 60 to 100⁰C, cooling down the mixture to a temperature in a range of 0 to 30⁰C and aerating the mixture.

The aqueous foam may be prepared separately and subsequently added to the food product. In another preferred embodiment of the process of the present invention, the aqueous foam may be formed in situ in the presence of the food product, i.e. the aqueous foam is directly prepared in the food product to be foamed.

In a particularly preferred embodiment of the process of the present invention, the aqueous primary foam and the food product to be foamed are mixed continuously to provide the shelf-stable final indulgent foamed food product.

The polysaccharide or hydrocolloid used in the formation of the aqueous foam is used in an amount of 1 to 60 wt.-% based on the components of the aqueous foam. Preferably, the amount of polysaccharide is in a range of 10 to 50 wt.-%. More preferred, the amount of polysaccharide is in a range of 20 to 40 wt.-%.

In principle, any polysaccharide may be used in the formation of the aqueous foam provided that it is water soluble and little sweet. In a preferred embodiment of the process of the present invention, the polysaccharide is selected from at least one of starch, cellulose and derivatives thereof . In a particular embodiment of the invention the polysaccharide is a starch derivative. Most preferred, the starch derivative is maltodextrin.

Further, hydrocolloids may be used such as carrageenan, guar, caroube acacia gums, xanthan and alginates.

In the process of the present invention the ingredient capable of forming interfacially active particles are preferably used in a range of 0.5 to 10.0 wt.-% based on the components of the primary aqueous foam. More preferably, the amount is in a range of 1.0 to 5.0 wt.-%, 1.0 to 3.0 being most preferred.

The ingredient capable of forming interfacially active particles corresponds to those as described above.

In a preferred embodiment of the process of the present invention, the ingredient capable of forming interfacially active particles is a lamellar phase forming surfactant selected from sodium stearoyl lactylate (SSL) , calcium stearoyl lactylate (CSL) , salts of fatty acids, lactic acid ester of monoglycerides (LACTEM) , citric acid ester of monoglycerides (CITREM) , succinated ester of monoglycerides (SMG) , diacetyl tartaric acid ester of monoglycerides (DATEM), phospholipids, sucrose esters, polyglycerol esters, propylene glycol stearate, sorbitan monostearate (SMS), sorbitan tristearate. More preferably, the at least one lamellar phase forming surfactant is sodium stearoyl lactlyate (SSL) .

The primary aqueous foam can be aerated to high overruns . In a preferred embodiment of the process of the present invention, the aqueous foam is aerated to an overrun of up to 500 %. Preferably, the aqueous foam is aerated to an overrun in a range of 200 to 450 %, more preferred 50 to 300 %. The overrun in the final aerated indulgent product is ranging between 10 to 300 %, more preferably between 25 to 150 %.

In principle any food product may be foamed by the process of the present invention. Due to the absence of fat, virtually all food products can be foamed. The use of a polysaccharide having a low sweetness allows foaming of non- sweet food products. In a preferred embodiment of the process of the present invention, the aqueous foam can be combined with a food product selected from ice cream mixes, sorbet mixes, dessert mousses, dairy products, fermented dairy products, soups, sauces, mayonnaise and beverages, dressings, liquid dairy products, creams, imitation creams, concentrated milks, condensed milk, non- dairy creams, toppings, chilled dairy, confectionery fillings, candies, dough, batter.

There is no particular limitation as to the mix ratios of the aqueous foam and the food product. As an example, the aqueous foam is mixed with the food product in a proportion of 1:3 in a regular continuous mixing device. However, other mixing ratios are appropriate depending on the food product to be foamed.

In the final product, 0.1 to 50 percent by weight (based on the finished food product) comes from the pre- formed aqueous bubble dispersion.

It has been shown that the foamed food products produced according to the process of the present invention are stable for a long time, even at room temperature. Reference is made to Fig. 3 showing a comparison between a foamed food product stabilized with 0.5 % SSL according to the present invention and a foamed food product aerated using a conventional process. As can be seen from Fig. 3, the foamed food product produced according to the present invention is stable over a time period of more than 24 hrs at 40⁰C . In contrast thereto, the foamed product produced using a conventional process is less stable since 10% of the foam volume is lost after 24 hours at 40⁰C.

The foaming procedure according to the process of the present invention enables the production of shelf-stable food product foams . The produced foamed products are storable at temperatures above 0⁰C, even room temperature without loosing the gas present in the form of tiny gas bubbles in the product. It has been shown that the two- step foaming procedure of the process of the present invention results in improved aerated viscous bulk phases. The aqueous foams stabilized with the at least one lamellar phase forming surfactant such as SSL can be made with high overruns of up to 500 %.

A further advantage of the process of the present invention is that the bubbles which are created in the first step, i.e. the step of forming the aqueous foam, can be mixed in-line with the viscous food product without coalescing, i.e. without loosing their stable interface properties created in the first step. As depicted in Fig. 4 the bubble size distribution obtained with the described process is generally narrower than the microstructure obtained with a conventional whipping process. This difference leads to different textures and different sensorial attributes in the final foamed product.

The shelf-stable foamed product produced according to the process of the present invention have an improved and modular product texture by controlling the gas bubbles size distribution and overrun. This provides a more stable foaming process. The foamed food products produced can be stored e.g. at 4⁰C or even at room temperature. The foamed food product produced are excellent light and low- fat stable products as the gas bubbles take the place of oil droplets .

Example 1: Mousse dessert The operation is carried out as indicated above using the following recipe to obtain a final indulgent aerated product with an overrun of 100% and having a dry matter content of the order of 34%. The aqueous phase is whipped up to 400% overrun and then continuously mixed and diluted four times with the dairy recipe. A final product is obtained which is very well preserved for 6 weeks at +4⁰C and which remains quite firm without any separation. The bubbles remain homogeneously dispersed. The final product can also be stored at subzero temperatures, i.e., down to -30 to -50⁰C, in its frozen state, and thawed back to room temperature without loosing its original foam structure. A narrower bubble size distribution and firmer texture is obtained compared to a conventional whipping process where all the ingredient are mixed together.

Ingredients Aqueous phase Dairy recipe

Whole milk - 60.50 %

Cream (35%) - 18.20 %

Sugar - 11.60 %

Skimmed milk powder - 6.60 %

Gelatin - 2.50 %

Emulsifier SSL (Danisco) 2.00 %

Maltodextrin DE21 50.00 % amidon - 0.60 %

Water 48.00 %

Example 2 : Coffee Mousse

The procedure is carried out as above, the only difference is the composition of the aqueous phase and of the dairy recipe . The final coffee foam can be stored at least for one month at 4⁰C without any separation. The aqueous foam is whipped up to 300% overrun and then diluted three times by continuous mixing with the dairy recipe. A narrower bubble size distribution is observed in the product obtained by using the above process.

Ingredients Aqueous Dairy phase recipe

Whole milk - 60.50 %

Cream (35%) - 18.20 %

Sugar - 11.60 %

Skimmed milk powder - 6.60 %

Gelatin - 2.50 %

Emulsifier Datem (Danisco) 2.00 % -

Maltodextrin DE21 40.00 % -

Coffee Extract - 1 %

Water 58.00 % -

Example 3 : Filling for confectionery

The product is obtained as the preceding examples. The aqueous phase is aerated up to 300% overrun and then diluted 3 times with the Chocolate base. The final foamed product can be used as a filling cream for confectionery products and can be kept at room temperature for several weeks .

Ingredients Aqueous Chocolate phase Base

Cocoa powder - 15.00 %

Fat mix - 20.00 %

Cocoa butter - 10.00 %

Skimmed milk powder - 10.00 %

Glucose syrup 40.00 % 15.00 %

Emulsifier SSL (Danisco) 1.50 % -

Sugar 15.00 % -

Sorbitol powder 20.00% 10.00 %

Water 23.00 % 20.00 %

Potassium sorbate 0.02% 0.01%

Claims

1. An aqueous foam comprising gas bubbles that are stabilized by food-grade, interfacially active particles selected from the group consisting of particles made out of seeds, spices, spores, grains, sugar crystals, lamellar surfactant crystals, nutrient crystals, particles made out of protein aggregates, particles made out of polysaccharide aggregates, particles made out of protein- surfactant aggregates, particles' made out of protein- polysaccharide mixtures, particles made out of polysaccharide-polysaccharide mixtures, particles made out of polysaccharide-protein phase separating mixtures, and mixtures thereof .

2. The foam according to claim 1 wherein a polysaccharide or hydrocolloid is present in an amount of 1 to 60 wt.-% based on the components of the aqueous foam.

3. The foam according to claim 2 wherein the amount of polysaccharide or hydrocolloid is in a range of 10 to 50 wt . - % .

4. The foam according to claim 3 wherein the amount of polysaccharide or hydrocolloid is in a range of 20 to 40 wt . - % .

5. The foam according to any one of claims 2 to 4 wherein the polysaccharide is selected from at least one of starch, cellulose gums and derivatives thereof.

6. The foam according to claim 5 wherein the polysaccharide is a starch derivative.

7. The foam according to claim 6 wherein the starch derivative is maltodextrin.

8. The foam according to any one of claims 2 to 4 wherein the hydrocolloid is selected from carrageenan, guar, caroube acacia gums, xanthan and alginates.

9. The foam according to any one of claims 1 to 8 wherein the food-grade, interfacially active particles are present in an amount of 0.5 to 10.0 wt.-% based on the components of the aqueous foam.

10. The foam according to claim 9 wherein the amount of the food-grade, interfacially active particles is in a range of 1.0 to 5.0 wt.-%.

11. The foam according to any one of claims 1 to 10 wherein the food-grade, interfacially active particles are selected from seeds, spices, seasonings, spores, cloves, pepper, fennel, cumin, coriander, nutmeg, poppy grains, paprika, cinnamon, talcum, pollen of flowers, wheat germs, wheat bran, saffron, coconut, cacao, melanoidins, sugar crystals, milk proteins, ginger, curry, cell wall material, nutrient crystals, phytosterol crystals, cholesterol crystals, hesperidin crystals, lycopene crystals, carotenoid crystals, flavonoid crystals, antioxidant crystals and mixtures therof .

12. The foam according to any one of claims 1 to 11 wherein the food-grade, interfacially active particles are made from a lamellar phase forming surfactant selected from sodium stearoyl lactylate (SSL) , calcium stearoyl lactylate (CSL), salts of fatty acids, lactic acid ester of monoglycerides (LACTEM) , citric acid ester of monoglycerides (CITREM) , succinated ester of monoglycerides (SMG) , diacetyl tartaric acid ester of monoglycerides (DATEM), phospholipids, sucrose esters, polyglycerol esters, propylene glycol stearate, sorbitan monostearate (SMS) , sorbitan tristearate (STS) and mixtures thereof .

13. The foam according to claim 12 wherein the food-grade, interfacially active particles are formed of sodium stearoyl lactylate (SSL) .

14. The foam according to any one of claims 1 to 13 having an overrun of up to 500 %.

15. The foam according to claim 14 wherein the overrun is in a range of 200 to 450 %.

16. The foam according to any one of claims 1 to 15 wherein the water content is up to 90 % based on the components of the foam.

17. A food product comprising an aqueous foam according to any one of claims 1 to 16.

18. The food product according to claim 17 wherein the food product is selected from ice cream mixes, sorbet mixes, dessert mousse mixes, dairy products, fermented dairy products, soups, sauces, mayonnaise and beverages, dressings, liquid dairy products, creams, imitation creams, concentrated milks, condensed milk, non-dairy creams, toppings, chilled dairy, confectionery filling, candies, dough, batter.

19. The food product according to claim (s) 17 and/or 18 having an overrun in a range of 10 to 300 %.

20. The food product according to claim 19 wherein the overrun is in a range of 25 to 150 %.

21. A process of producing a shelf-stable foamed food product comprising the steps: forming an aqueous foam comprising water, at least one polysaccharide or hydrocolloid and interfacially active particles and adding said aqueous foam to a food product.

22. The process according to claim 21 wherein the aqueous foam is formed by heating a mixture containing water, at least one polysaccharide or hydrocolloid and the ingredient being able to form interfacially active particles to a temperature in a range of 60 to 100 ⁰C, cooling down the mixture to a temperature in a range of 0 to 30 ⁰C and aerating the mixture.

23. The process according to claim (s) 21 and/or 22 wherein the aqueous foam is prepared separately and subsequently added to the food product .

24. The process according to claim(s) 21 and/or 22 wherein the aqueous foam is prepared in the food product to be foamed.

25. The process according to any one of claims 21 to 24 wherein the aqueous foam and the food product are mixed continuously.

26. The process according to any one of claims 21 to 25 wherein the polysaccharide or hydrocolloid is used in an amount of 1 to 60 wt.-% based on the components of the aqueous foam.

27. The process according to claim 26 wherein the amount of polysaccharide or hydrocolloid is in a range of 20 to 50 wt. -%.

28. The process according to claim 27 wherein the amount of polysaccharide or hydrocolloid is in a range of 20 to 40 wt . -%.

29. The process according to any one of claims 21 to 28 wherein the polysaccharide is selected from at least one of starch, cellulose gums and derivatives thereof.

30. The process according to claim 29 wherein the polysaccharide is a starch derivative.

31. The process according to claim 30 wherein the starch derivative is maltodextrin.

32. The process according to any one of claims 21 to 28 wherein the hydrocolloid is selected from carraghenan, guar, caroube acacia gums, xanthan and alginates.

33. The process according to any one of claims 21 to 32 wherein the interfacially active particles are used in a range of 0.5 to 10.0 wt.-% based on the components of the aqueous foam.

34. The process according to claim 33 wherein the amount of interfacially active particles is in a range of 1.0 to

5.0 wt . - % .

35. The process according to any one of claims 21 to 34 wherein the interfacially active particles is selected from particles made out of seeds, spices, spores, grains, sugar crystals, nutrient crystals and lamellar surfactant crystals selected from sodium stearoyl lactylate (SSL) , calcium stearoyl lactylate (CSL), salts of fatty acids, lactic acid ester of monoglycerides (LACTEM) , citric acid ester of monoglycerides (CITREM) , succinated ester of monoglycerides (SMG) , diacetyl tartaric acid ester of monoglycerides (DATEM), phospholipids, sucrose esters, polyglycerol esters, propylene glycol stearate, sorbitan monostearate (SMS) , sorbitan tristearate (STS) and mixtures thereof.

36. The process according to claim 35 wherein the ingredient being able to form interfacially active particles is sodium stearoyl lactylate (SSL) .

37. The process according to claim 35 wherein the food- grade, interfacially active particles are selected from seeds, spices, seasonings, spores, cloves, pepper, fennel, cumin, coriander, nutmeg, poppy grains, paprika, cinnamon, talcum, pollen of flowers, wheat germs, wheat bran, saffron, coconut, cacao, melanoidins, sugar, milk proteins, ginger, curry, cell wall material, nutrient crystals, phytosterol crystals, cholesterol crystals, hesperidin crystals, lycopene crystals, carotenoid crystals, flavonoid crystals, antioxidant crystals and mixtures thereof .

38. The process according to any one of claims 21 to 37 wherein the aqueous foam is aerated to an overrun of up to

500 %.

39. The process according to claim 38 wherein the overrun is in a range of 200 to 450 %.

40. The process according to any one of claims 21 to 39 wherein the food product is selected from ice cream mixes, sorbet mixes, dessert mousse mixes, dairy products, fermented dairy products, soups, sauces, mayonnaise and beverages, dressings, liquid dairy products, creams, imitation creams, concentrated milks, condensed milk, non- dairy creams, toppings, chilled dairy, confectionery filling, candies, dough, batter.

41. Use of an aqueous foam according to any one of claims 1 to 20 for producing a shelf-stable foamed food product.